Construction of pavements



(No Model.)

s. W. GRAGG. CONSTRUCTION 01? PAVEMENT-S..

No. 315,740. Patented Apr. 14, 1885.

' UNITED 'STATES PA'rrnNr @Priora SAMUEL XVILKINS CRAGG, OF BALTIMORE,MARYLAND.

CONSTRUCTION OF PAVEMENTS.

SPECIFICATION forming part of Letters Patent No. 315,740, dated April14, 1885.

Application filed June 10, 1884. Renewed March 13, 1865.

in Span September 26, 18:91, No. 6,075.

(No modehl Patented in France April ill, 18S-i, No. 149,126, and May-l,

No. 16,815; in Austria August :'12, 138i, Ill/1,483, and

To @ZZ whom, may concern:

Be it known that l, SAMUEL Wi LnrNs CBAGG, of the city of Baltimore,State of Maryland, have invented certain Improvements in theConstruction of Pavements, of which the following is a specication.

The object of this invention is to reduce the cost of wood pavementsWithout affecting their efficiency, and to provide various advantages,hereinafter set forth, not procurable by any of the systems heretoforeinuse. In wood pavements as heretofore constructed the blocks employed areall of the same dimensions-that is to say, each block is of the samelength, breadth, and thickness as all the other blocksthese blocks beingplaced endwise on a foundation having a smooth or even surface.Therefore the blocks used at the sides of a street, or in proximity tothe curbs, are just as long or deep as those in the middle or at anyother part of the road-that is to say, each block projects upward fromthe surface of the concrete or other bed an equal dist-ance. Theconsequence is that the strength of the pavement is the same at thoseportions thereof which are subject to slight wear as at the portionsWhich are subject to considerable wear, and as an example of thedisadvantage of this arrangement it may be statedthat in very narrowstreets and upon bridges there are certain parts of the roadway whichare never used either by horses or wheels. It will, therefore, beunderstood that in such cases there is a useless consumption of valuablematerial-i. c., wood, When Wood is used.

My invention consists in employing blocks of different length-that is tosay, blocks which, when placed on end in the position they arey tooccupy, will not all extend to the same depth 5 also, in constructingthe bed in a special manner suitable for the reception of such blocks,as hereinafter described.

In carrying my said invention into practice I provide afoundation or bedof concrete or other suitable material, made in longitudinal tiers orsections of different heights, so that while the upper surface of theroadway will be smooth and even and will conform to the curve given tothe foundation, the blocks forming the said surface will be long orshort u vertically, according to the section of the bed y upon whichthey are placed. For instance, the surface of the foundation in thecenter of the roadway is at a low level to admit the longest or deepestblocks being placed at that 5 part, and on each side of this centralportion toward the curbs there are other sections arranged at higherlevels, so as to take blocks shorter or of a less depth when on end atparts where the traffic is not so heavy. Any eonvenient number of suchlongitudinal sections may be employed according to the require ments inany ease.

In order to obtain a perfect adjustment of the top surface, I spreadover the surface of 6 the different sections thus prepared a very thinlayer of dry cement, sawdust, asphalt, or other material in tine powder.These yielding substances, besides facilitating a perfect adjustment ofthe top surface, allow liquid cement or asphalt poured on the blocks torun in around and under the same by being absorbed by the dry powderedmaterial. It will thus be seen that by my invention I am enabled to adjust t-he depth of the blocks according to the eXi- 7 gencies of thetraffic of different portions of the transverse area of the road.

A further advantage of my invention is that repairs are facilitated, asone section that is Worn may be readily repaired Without inter- 8 feringwith any other section which is still serviceable, whereas by reason ofthe uniformity of the blocks in pavements as heretofore made, it isdifficult to repair one part without taking up the whole. Moreover, bymeans of my system of making the foundation I am enabled to build eachsection separately. For example, in wide roads the central section maybemade first, leaving the two sides open to traffic. The longitudinalsections of thefoundationare much more readily made than the Wide singlecurve ordinarily used, which requires the services of expert engineers;and another feature in favor of my invention is that instead of havingto eXcava-te the roadway to the same depth entirely across, asheretofore, I need excavate to the full depth only at the center.

In the further description of my said invention which follows, referenceis made to the accompanying drawings, forming a part hereof, and inwhich- Figure I is atransverse section of a streetpavement, showing thelength or depth of the sections of the blocks as decreasing toward thecurbs. Fig. II is a similar view of a much narrower street or singlebridge, with sections of `blocks and foundation arranged differently.

Referring to Fig. I, A, B, and C are the blocks resting on a foundationpreferably of concrete. The blocks A have the greatest depth and formthe central section of the pavement, and the blocks B, which are of lessdepth than the ones A, the first of the side sections. The blocks C,which have the least depth, adjoin the curbs E.

In Fig. II, which represents a much narrower street than the one shownin Fig. I, the blocks A form the central section, and the blocks B areplaced next to the curbs. The

blocks of least depth, C, are situated between the deeper sections.

I am aware that in wood pavements blocks of different sizes have beenarranged so that blocks of about the same circumference or area 1 ofcross-section are laid in the same row, the rows extending transverselyor diagonally of the street, or the blocks arranged in groups, thesmaller blocks being placed on a higher foundation'than the larger ones,and then rammed down to give them a more solid foundation or bed, andsuch construction and arrangement of blocks I do not claim; but I am notaware that wood blocks have been arranged in sections of differentdepths extending longitudinally of the road or street, for the purposedescribed.

I therefore claim as my invention- 1. In a wood pavement, the foundationthereof made of concrete or other suitable material, in tiers orsections of different heights, which extend longitudinally of theroad-bed or street, substantially as and for the purpose specified.

2. In a wood pavement, the blocks thereof of different lengths ordepths, arranged in tiers or sections which extend longitudinally of thepurpose specified.

SAMUEL WILKINS CRAGG. Witnesses:

GEORGE WALKER, EDWIN AGOSTINI.

road-bed or street, substantially as and for the ,g

